A short video posted to YouTube by the Ukrainian government reportedly shows a “Buk,” or SA-11 “Gadfly,” surface-to-air missile system en route from eastern Ukraine to the Russian border on Friday.

While the video cannot be independently verified, the footage appears to show the system with at least one of its missiles missing. It also appears to be mounted on a tracked chassis, although it has been loaded onto a flatbed trailer. Tracked vehicles are decidedly slower than their wheeled counterparts. The use of the truck could indicate the system’s own propulsion system is disabled, or that speed is a priority for whomever is moving it.

U.S. officials asserted Friday that the Malaysian airliner that crashed in Ukraine was likely downed by an SA-11 operated from a separatist-held location.

The SA-11 is only one variant of the Buk family of medium-range surface-to-air missiles that have been in service since the late 1970s. A newer model, the SA-17, has a longer engagement range and engagement altitude due to an enhanced radar tracking system that extends on a telescopic arm. Missiles fired by the newer variants can reach up to 70,000 feet, more than twice as high as MH17’s cruising altitude.

Both the SA-11 and SA-17 can be interfaced with other anti-aircraft systems through a command vehicle, creating a specific air defense grid for certain missions or defensive postures. Both systems can also be used in a standalone mode and can target aircraft with their on-board radars, regardless of whether there is a command vehicle present.

If such a missile system was used to down the MH17, it most likely would have been operating in standalone mode, as intelligence reports have indicated that the U.S. detected only one active anti-air radar system in the vicinity of the shoot-down.

While the SA-11 and SA-17 can fire a variety of different missiles, their average missile speed is roughly three times the speed of sound, or Mach 3, meaning the missile can travel approximately 89,000 feet per minute once it reaches top speed.

If the launcher was directly underneath MH17 when it fired, which it most likely wasn’t, the missile would have taken a little over 20 seconds to reach the airliner.